Hydraulic brake booster



March 16, 1954 F, ADAMS 2,672,015

HYDRAULIC BRAKE BOOSTER Filed July l0, 1947 4 Sheets-Sheet 1 t: z/W R5 H. M wm M www, 2 ma n W Q 0 f mq M OV 6 4 5/ K w @l N .L /Z nh 5 5 444 .5 a e 4M znw n o Fw au H l N l N l F /M// /V w 2 M z f VV Q n Im -ml i 3 -1 uur 1|,| W M a ma w m a@ 8 @$5 8 n w m mw l mi 1% 6 Y@ l w H 4 F/ F. ADAMS HYDRAULIC BRAKE BOOSTER March 16, 1954 4 Sheets-Sheet Filed July 10, 1947 v INVENTOR. Efe/4MM y Hof-Wn 5 BY M M M ArToB//EVS F. ADAMS HYDRAULIC BRAKE BOOSTER March 16, 1954 Filed July 10, 1947 1N VEN TOR. F24/vx Hon/5 BY March 16, 1954 F. ADAMS 2,672,015

HYDRAULIC BRAKE BOOSTER Filed July 10, 1947 4 sheets-sheet 4 INVENroR.

7 Fen/vz Hon/5 T M,4MM

ATT ale/vs v5 I Patented Mar. 16, 1954 UNITED STATES ATENT OFFICE HYDRAULIC BRAKE BOOSTER Frank Adams, Milwaukee, Wis.

Application July 10, 1947, Serial No. 760,087

2s claims. (o1. en -54.5) Y

chambers of the multiple cylinders in communication with each other.

It is a further object of the invention to provide a novel and improved organization which can be used in any position and in which, notwithstanding the great amount of auxiliary power provided by the multiple pneumatic cylinders, the operator is given, at all times, the feel of the brake so that the resistance to his foot pressure is a constant gage of the degree of braking action.

Other objects will appear more specically upon analysis of the following disclosure of the invention.

In the drawings:

Figure 1 is a view in axial section through a device embodying the invention.

Figure 2 is a perspective view on a reduced scale showing the external appearance of the apparatus illustrated in Figure 1.

Figure 3 is a'detail View on a reduced scale taken transversely through the apparatus of Fig- ;;r

,ure l.

Figure 4 is an enlarged detail view in perspective showing the communication tube of the apparatus with portions broken away to expose interior parts.

Figure 5 is a fragmentary View in section showing a modified arrangement of the control casing and its valves.

Figure 6 is a view partially in elevation andl partially in section showing on a reduced scale and partially in diagrammatic form a modification of the device of Figure l in which the control casing is entirely removed from the booster cylinder assembly.

Figure '1 is a view partially in section and partially in side elevation showing a modified ernbodiment of the invention.

Between the mounting brackets 8 any desired number of pneumatic cylinders are assembled withcommunications in parallel subject to autor matic control as hereinafter described. mechanical assembly is as follows:

Connected by cap screws 9 to the respective brackets are the shouldered heads lil of aligned stationary pistons I, l2. Guided upon these for axial reciprocation is the oating hydraulic cylinder member I5 which has cylinders I6, I1, opening to its respective ends and in which the stationary pistons II and I2 operate with suitable packing as shown. The floating cylinder member I5 .has a transverse partition I8 between the cylinders i6, I1. There is a valve port I9 affording communication between the cylinders subject to the control of a valve 20, the stem of which extends loosely through port I9 and is provided at 2| with a collar which, in the position of the parts illustrated in Figure l, is engaged by the tapered wall of a recess 22 in the end of sta- The tionary piston I2. The periphery of the collar 2| is polygonal so that it may engage the wall of recess 22 without precluding free communication past the collar. The compression spring 23 acts upon the collar in a direction such as to tend to seat the valve 20 to close port I9 save when the valve is held open by engagement of the collar with piston I2 when the piston is fully received into its cylinder I1.

Ihe cylinders I6, I1 form a part of the hydraulic circuit between the diagrammatically illustrated master cylinder 23 and the brake cylinders 24. The pipe 25 communicates with the master cylinder 23 through fitting 26 and duct 21 which opens into the recess 22 of piston I2. A similar recess 28 in the end of piston I I opens into duct 29 which communicates through fitting 30 with pipe 3| with the valve cylinder or cylinders 24 of the brake system. When the floating cylinder member I5 is in the position illustrated in Figure 1, the valve 20 is forced open to equalize hydraulic pressures throughout the hydraulic system. In this position of the parts any additional pressure imposed on the master cylinder by manipulation of the brake pedal will be communicated in the usual way through pipe 25, duct 21, cylinder I1, port I9, cylinder I6, duct 29 and vpipe 3| to the brake cylinders. Upon relief of pressure on the brake pedal, the oil will return from the brake line 3| toward the master cylinder in like manner.

Surrounding the hydraulic system as above described, I provide between the brackets 8 any desired number of pneumatic cylinders. I have shown two such'cylinders in Figure 1 and three in Figure '1. It will be evident that more may be provided as needed. The pneumatic cylinders `with passages 43.

35, 36, 3l (the latter being shown only in Figure 7 and being typical ci any desired number of added cylinders) may conveniently be made of cupshaped stampings marginally secured together. The cup-shaped elements i3, I4 at the ends of the series may conveniently be held by the cap screws 9 to brackets 8, suitable packing being preferably provided at 39. The complementary cup-shaped elements 39, 40 may conveniently have their inner margins anchored in a spacer ring 4I which is provided at 42 with suitable packing engaging the periphery of a sleeve which is brazed or otherwise secured peripherally to the iioating cylinder member: to; complete the enclosure of passages provided by the alternating slots 43, 44, cut longitudinally-in the exterior surface of such member. They slots 43 all open toward the end of member i5 which is uppermost as viewed in Figure 1 while slots 4# all open only toward the end of member I5 which lowermost in Figure 1. The sleeve:` |51 has openings registering with the blind ends of slots; 4.41 The sleeve has* openings at. 4,8@ communicating with. thel blind: ends of. the: passages 4'3;

In each or"y thepner-.matic cylinders, there isi a diaphragm-packed piston 41, 43, 4.9i (the latter appearing only in Figurev 7); Each piston" preferably comprises a pair of: like stampings 5E. .Tn

the case` of the pneumatic cylinders: 35 and 3S,

the stampings- 55 areV clamped against the ends of the sleeveY lei' by nuts 52', 53 which are threadedv to the floating cylinder memberv I5 and are notched at 54: to communicate with the open ends off passages i3 and at to communicate with the open ends of passages 44, respectively. Suitable channels at 56. in the piston elements 59 receive the annular beads or ribs 51 with which the diaphragms 58, 59 are provided'. The ex:-

terior' peripheral' margins ofthe respective diaphragms are clampedV between the cup-shaped stampings |'3', 39 which make up pneumatic cylinder 35V and the corresponding stampings |'4`, 4|) which make up pneumatic cylinder 36, the assembly being maintained by bolts 6|.

In Figure '7, the central' pneumatic cylinder 311 typifies the manner in which any desiredV number of additional cylinders may be introduced between'- cylinders 35 and 36, the iioatin'g cylinder member |581 and its sleeve |52 and the stem of 'i valveV 20?' being lengthened accordingly. As many spacer rings 41| 0, i I'I, as may be required, are used to provide mechanical connection between the respective pneumatic cylinders. Each ring has a packed.` bearing through which they hydraulic cylinder' and sleeve are unitarily slidable'. To the reciprccable cylinder member |r` and its sleeve |52', the pistons tlf and 48 in the terminal pneumati'ci cylinders. 35. and 36 are attached by. nuts 52;. 53A in the manner.` already described' The piston or pistons 59 of any intervening pneumatic cylinder; or cylinders may be mounted between collars 64, 65 xedj upon the exterior-of sleeve |52'. For eachl intermediate'- pneumatic cylinder, orices 450V in. sleeve |52` will aiford communication to the passages 44, while orifices 46.0 will afford communication at the other side of. the piston,

Thru passages 43 and 4.4, corresponding portions of all cylinders-v are, incommunica'tioir Thus,l regardless of how many pneumatic cylinders may be incorporated in the assembly, such cylinders comprise a substantially rigid. unit extending between the brackets. 8v and the reciprocable,-. floating. cylinder member' I5 extends through all of the pneumatic cylinders in the series and is telescopically guided on the pistons fixed at the terminals in the series.

While the pneumatic cylinders may be regarded `as mechanically connected in series, their pneumatic connection is in parallel. It is this fact which makes it possible to add pneumatic cylinders as may be desired to multiply the braking power exerted. In Figure 7 pistons H0, |29 i'xed to the brackets 8, are identical with those shown at I| and I2 in Figure l` save that they have been reduced in weight by cutting them away peripherally, a feature which may likewise be; adopted in the case oi the pistons and I2 if desired.

A Vacuum line 65 connects to the low pressure sideeoi? the pistonin one ci the pneumatic cylinders. The preferred connection is through the cup-shaped element I 3 of the pneumatic cylinder 35. The compression spring 9S which acts on. theV floating; cylinder mem-ber I5 and the pistons connecte-:l therewith is also preferably lo'- cated'` in this cylinder, although it. may be elsewhere. Through the notches 5ft of nut 52 and by means of the longitudinally extending slots or p'.=.ssagesv 43. and the orifices i6 or 466, the low pressure chamber of. pneumatic cylinder 35 is placed in` communication, with the low pressure chambers of each and' every' other pneumatic cylinder in. the series- By means oi. the notches of nuit 53 andthe communicating channels or passages M, the high pressure chambers of the respective pneumatic cylindersv are all in com'.- rnunieation. Thus the pressures on the corresponding faces of the several pneumatic pistons d?, i9 and lit are equalized throughout the` series of'pneumatic cylinders.

`vlihether two or more pneumatic' cylinders are employed, they are preferably encircled byy a band lli, l I', a portionoi which is foraminous, as shown in Figures 1, 2, 3 and 7 to admit atmospheric air through the arcuate lter body 73 and the inner foraminous` wall 'll to an air chamber 'I5 conveniently located between two of. the pneumatic' cylinders. The lter body i3, which may be of anyl suitable material, frees from dust and water the atmospheric air admitted to the air chamber l5.

Disposed in the air chamber between such cylinders is the valve control casing generically designated by reference Character iii, fer which the shell 'l may be embossed outwardly in the manner shown in Figure4 2. This casing is mounted in any convenient manner. For example, I have shown it in Figure. l to be welded at il to the cup-shaped element 59 of air cylinder 35' and it is also welded at lil' to theY cup-shaped element t8 of pneumatic cylinder 315 (in the case of the device. shown in Figure '7, the connection is made to pneumatic cylinder 3l instead ci pneumatic cylinder 3.5i..

-Atthe smallerend. of the control casing 'Z6 is an air inlet port 5B controlled by a valve El slidably mounted on a connecting rod d2 shouldered at' 83. When valve iii is open, port 85 provides communication from air chamber to control chamber 84. which is formed by a partition S5 across the casing it. In the partition is another valve port at 8S controlled by a valve Si', likewise slidable upon the connecting rod 82; A compression spring S seated against the respective valves 8|, 3l' biases themv oppositely toward their respective seatsl to the extent permitted by the respective shoulders 3.3 and Eil, theV latter being provided. byY ay fitting: 9.a mounted. on. the, connect'- ing rod 82 which serves as the valve stem for both valves and permits sliding movement of the respective valves to and from the shoulders which limit the opposite extremes of such movement.

At the inner end of connecting rod 82 is a piston 9| which operates in a cylinder 92 held by compression spring 93 in a socket 94 formed in one of the spacer rings 4I (or 4|0). Pipe 95 leads from the interior of cylinder 92 to the hydraulic pressure inlet fitting 26 whereby the control cylinder is placed in communication With the master brake cylinder.

At the end of connecting rod 82 opposite piston 9|, the connecting rod has attached to it a diaphragm piston 96 packed by diaphragm 91 and biased by spring 98. The nut 99 holds the diaphragm piston 96 to the fitting 90 on the end of the valve stem. A duct I I leads through the stem from the control chamber 84 to the back pressure chamber |02 in which compression spring 98 is located.

Operation is as follows:

It may be assumed that the booster device herein disclosed is employed to control the brakes of a vehicle Whose engine (not shown) is in operation. Through connection to the intake manifold of such an engine (or any other low pressure source), air is constantly being withdrawn through pipe 66 from the low pressure side of the several pneumatic cylinders. If there is no braking pressure being exerted on the master cylinder, there will be no hydraulic pressure in line 25 or line 95 communicating therewith. Under these circumstances, the spring 98 in the `control casing 16 will urge the connecting rod 82 i and its associated parts to the right as viewed in Figure 1, with the result that valve 8| Will be seated and valve 81 will be opened.

Through the eyelet seal the chamber |04 in regulating casing 16 is in communicationv with case of Figure 7) which, through the passages 4,4, is in communication with the high pressure portions of all of the other cylinders. Under the stated conditions, therefore, pressures on both sides of each of the pneumatic pistons 41, 48, 49 are balanced throughout the pneumatic cylinders and the floating cylinder I5 (I 50 in the case of Figure') is held by spring 68 in the position shown in Figures 1 and 5.

With the floating cylinder I5 (or |50) in the position illustrated in Figures 1 and 7, the contact of collar 2| with the end of piston I2 forces valve 20 open against the bias of spring 23. In consequence, there is open communication'for the hydraulic liquid from the master cylinder line through duct 21, port I9, cylinder I6 and duct 29 to the slave cylinder pipe 3| Whichleads to the several brake cylinders.

Assuming that pressure is now applied to the brake pedal to establish pressure in the master cylinder 23 and master cylinder line 25, the initial pressure is communicated directly through the open channels aforesaid to the slave cylinder line 3| to initiate response at the brakes. However, pressure is also developed in the' branch line 95 which leads to the `control cylinder 92.

piston 96 increase.

6 This pressure, acting on piston 9| and connecting rod 82, overcomes the bias of spring 98, closes valve B1 and ultimately opens valve 8|.A

As valve 81 closes, it cuts off communication between the high pressure sides of rthe operating cylinders and the low pressure sides thereof, as previously established through the control chamber 84 (which communicates through seal eyelet |01 with the high pressure sides of the several cylinders) and chamber |04 (which communicates by seal eyelet |05 with the low pressure sides of the several pneumatic cylinders). The opening of Valve 8| now admits atmospheric air from air chamber 15 through chamber 84 and eyelet |01 and passages 44 to the high pressure sides of the several pneumatic cylinders and establishes a pressure differential on the several pistons 41, 48, 49.

As the atmosperic air continues to be admitted, differential pressure is increased. The pistons and the iioating cylinder I5 (|56 in the case of Figure 7) advance against the bias of spring 68 to reduce the capacity of the hydraulic cylinder I6 by the entry of the stationary piston I to such cylinder. The first advance of the floating cylinder and associated pistons permits valve 20 to close under the bias of its spring 23 so that the liquid displaced from the hydraulic cylinder I6 must escape through duct 29 to the brake cylinder line 3| Where its pressure is exerted to operate the several brakes.

Meantime the chamber |02 in the control casing 16, which was originally subject to partial vacuum communicated thereto through duct |0I, is now subject to the atmospheric pressure in chamber 84 due to the closing of valve 61 and the opening of valve 8|. The chamber |04 remains subject to partial Vacuum (via eyelet |05, duct 43, pipe 66) and hence differential'pressure is established on the diaphragm piston 96 which is substantially proportioned to the differential pressures to which the pneumatic pistons 41, 48, 49 are subject. As the pressure on the pneumatic pistons increases, so does the pressure on This pressure is communicated through connecting rod 82 and piston 9| and the liquid in hydraulic cylinder 92 to pipe 95 and thence back through the master cylinder line 25 to the master cylinder, where it evidences itself upon the brake pedal. Consequently, despite the fact that the valve 20 has cut the master cylinder off from the braking circuit, the operator feels, upon the pedal, a resistance proportioned to the booster effect developed in the apparatus and the sensation in his foot is substantially the same as if the foot were actually eiiecting the braking operation. His foot being subjected at all times to a resistance comparable to the actual braking pressure, he is able to perceive through his foot the degree of such pressure with substantially the same sensitivity as if the braking operation were being performed directly by the'foot pedal instead of through the lbooster mechanism. i

Figure 5 shows a modified control arrangement. The control casing is generally similar in form and location to the control casing 16 previously described. Its smaller end has an annular iiange 890 constituting an outwardly directed Valve seat with which the valve 810 cooperates. This single valve is made to perform the functions of both of the valves 8| and 81 in the device of Figure 1. It is urged toward its seai 800 .by the compression spring 880, guided onf? post 8|I fixed inthe collar 4|. f

Within the. casing 'its the; shell B20; floats supportedand guided by the diaphragm 9?:0 andi by the bridge memberv 8de; which connects'J the shell with pis-tonele in hydraulicy cylinder 92o. The compression: spring des seated aga-inst` an inter.- nal shoulder in the; easing li urgesv the shell and diaphragmtotheflet as viewed inFigurel 5.. (Sec the; position of the parts in lgure 5.):

ShellY 82|) has a reducedneck portion Btc. which mayseat against the. valve Sililfwheneverthe shell movesto the right in easing 165, against' the: compression of spring dal)- This happens whenever the. brake pedalv is' depressed tov deliver pressure tromy the masterV cylinder.' 23. to pipes'l 21%.V and d.

The operation isthe same. functionally asithat already c crbed, although: the. parts are reversed' in th ir direction of movement.Y When there is no pressure on the master cylinderl the seat portion. 35d oi shell i226 is retracted from the valve; 81E, thereby affording communication through the annular seat Se@ liietifieenthehigh pressure. chambers ci the. several' pneumatic: cylinders (via eyclet seal itl); and` the low. pressure chambers (via eyelet seal; m51. When the initial braking pressure is applied, suchpressure is` corn.- municated through pip-e to cylinder' 92d thereby forcing piston dit to the right as viewed in vliigure This displaces.l the shell 32o: and its diaphragm until the sleeve. which provides seat 85D' contacts, the valve dit. munication between the high pressure and low pressure sides of the several pneumatic cylinders` is. cut. oir". Continued increment of the shell to` the right with piston SEE! will maintain the; seal' of the valve on seat Stil but will'. displace tl'rezvalveL 51'@ from; its seat 8%@ on stationary casing ld. This places atmospheric air in chainlieit 'l5 in communication through seatv dat eyelet |'0'5 with the highpressurechambers of the several'A cylinders.. Thereupon the pressure dit;- erentiall in such cylinders will' displace the pis.n tons therein to exert braking pressure as above described. Figure 5 shows the parts in this. po.- sition.

Figure 6 is included to demonstrate` the fact :c

thatv it. is not necessary that the control mecha;- nism be disposed between the pneumatic. cylinders 35 and St in the manner suggested in Figiures 1 and 5.v It can be` located at any' remote point. Under some. circumstancesI this may be desirable even though, it means that thecommu'- ni'cating piping will be exposed; This View further dem. strates the: fact.thatinasmuch as: the several pressure and low pressure chambers of. the; multiple pneumatic. cylinders are all'. in communication, each. with. the other, the particular point at which the pneumaticv connections are' made is. of: relatively little. consequence, Whereit` is desired to control the brakes of one or more trailers, a single control mechanism, remotely located, as suggested. in Figure 6, can obviouslyY be used to. regulate. the operation of any .desired number of boosters or slave motors provided the necessary branch pneumatic connections` are made.`

InA the device of Figure 6 the. casing'lll', except for the fact that it is definitely located and has no eyelet seals. |65 and |91, isaidenticalwith the casing 'idc oi Figure 5. The,v sameV valve seats and valves are provided. However thevalve: 8|0, instead of being located in an air chamber '|5 between two cylinders is now disposed. in an air chamber H3 andY supported by aspring: 88|.. A pipe.` connected with air: cleanerI H2 admits atmospheric air to chamber 1.1.0.

At this point the ccmsure. inV cylinder Thechamber 8M withinL casing '|61 isA connected by pipev I I3 with, the high pressure cham.- tierl H. or any one4 or morev of thel booster cylinders or slave; motors. Chamber |020', instead of being. connected directly with. the low pressure chambers of any one of the cylinders is simply connected by branch 'pipe 660 with the vacuum line. through which it is in communication wtih all of the low pressure chambers.. The operation is exactly the same as above described. Moreover, it will be understood that the type of control mechanism shown in vFigure l is also usable in. a remote location in the manner suggested in Figure 6.

'Ehe slavev motor llo shown in Figure 6 is identical with any one of: the boosters heretofore described except that, being a slave motor and remote; from any' braking pedal operation, it requires no hydraulic connection at 26 except to the rest-.rye` oil. tank I5 communication with which is controlled by the check valve Z3. Branch vacuum and air connections are provided at 561 and: ||3llf from pipes Et@ and |53 respectively. Such. a. slave motor. Will develop hydraulic pres- I: and apply such pressure through its own brake line 3| in unison with the operation of the main. booster as regulated by the control mechanism, whether integrated or remotely located. While the size of the slave motor ||5 has been reduced for diagrammatic illustration, it will. be understood that it may have any desired size.

I claim:

1'. In. a device of the character described, the combination with a. plurality of pneumatic cylinders. connected end to end inseries, of a stationary hydraulic piston within one of said pneun matic cylinders having a face and an internal conduitv openingrv through the piston from said face, a hydraulic cylinder reciprocable within said pneumatic cylinders and guided in part on said hydraulic piston, and a pneumaticl piston in: each of' said pneumatic cylinders, said pneu maticI pistons being connected with said hydraulic cylinder to reciprocate in unison therewith, said pneumatic pistons dividing the respective pneumatic cylinders into high and low pressure chambers, and passages extending through the hydraulic cylinder and opening into the respective corresponding chambers of said pneumatic cylinders, thereby placing the respective high pressure chambers of said pneumatic cylinders in communication with each other andthe respective low pressure chambers of said pneumatic cylinders in communication with each other.

2. In a. device or the character described, a floating hydraulic cylinder member provided' in teriorly with a cylinder cavity and with longitudinally extending passages externally of said cavity, a rst pneumatic piston mounted on said member and through. which at least one of. said passage opens, a second pneumatic piston mounted on said member remote from the rst and through which a. dinerent opens, the first mentioned passage opening` through said member adjacent said secondpiston, and thev second passage opening through said. member adjacent the irst piston, a iirst pneumatic cylinder in which said first piston is operable, a hydraulic piston disposed in said pneumatic cylinder and coacting with the cylinder` cavity of said member, and a second pneumatic cylinder in which theisecond pneumatic piston is operable, each of said pneumatic pistons havingv means sealing it regarding its. respectiva pneumatic cylinder, each 9 of the pneumatic cylinders having high pressure and low pressure chambers, and the high pressure chambers of the respective pneumatic cylinders being in communication through one of said passages, and the low pressure chambers of the respective pneumatic chambers communicating with each other through the other of said passages.

3. In combination, a series of pneumatic cylinders, a pneumatic piston operable in each and provided with a seal to its respective cylinder, a power transmitting member to which the respective pneumatic pistons are connected, the pneumatic cylinders of said series having bearing means through which said member is reciprocable, cylinders in said member, said member having a ported partition between said cylinders, a normally seated valve controlling flow through the port of said partition, hydraulic pistons xed in the terminal pneumatic cylinders of said series and extending toward each other and operatively engaged in the cylinders of said member, one of said hydraulic pistons having a portion in the path of said valve for the unseating thereof at an extreme position of said member, a spring biasing said member toward said extreme position, and hydraulic connection to the respective hydraulic pistons, each of said hydraulic pistons having a passage aifording communication between the hydraulic connections and the cylinders of said member.

and operatively engaged in the cylinders of said member, one of said hydraulic pistons having a portion in the path of said valve for the unseating thereof at an extreme position of said member, a spring biasing said member toward said extreme position, and hydraulic connections to the respective hydraulic pistons, each of said hydraulic pistons having a passage affording communication between the hydraulic connections and the cylinders of said member,

together with hydraulically operable valve mechanism for controlling differential pressures in the pneumatic cylinders whereby to effect piston movement therein to actuate said member.

5. The device of claim 4 in which said pneumatic pistons divide said pneumatic cylinders into corresponding chambers, said member being provided with longitudinally extending passages opening into respectively corresponding chambers of the respective pneumatic cylinders whereby relative pressure differentials in each thereof will correspond.

6. The combination set forth in claim 4 inY which said pneumatic pistons divide said pneumatic cylinders into corresponding chambers, said corresponding chambers of the respective pneumatic cylinders being provided with communicating passages, said control mechanism comprising a vacuum connection communicating with said pneumatic cylinders at corresponding sides of the pistons therein, valve means whereby lo. said chambers of the respective cylinders at the opposite sides of their respective pistons may selectively be placed in communication either with said vacuum connection or with the atmosphere, and a branch hydraulic pressure line communicating with the hydraulic passage in the hydraulic piston having the valve displacing por; tion, said hydraulic line including a' further piston operatively connected with said last mentioned valve means for the actuation thereof.

7. In a device of the character described, a plurality of pneumatic cylinders each comprising a pair of pans peripherally flanged and dished in opposite directions, a bearing collar connecting contiguous pans in the series, a piston fitting in each of the terminal pans of the series, each fitting having a piston projecting axially within the series, and each piston having a conduit opening therethrough externally of the series, a pressure input line connected with the conduit of one of said pistons and a pressure delivery line connected with the conduit of the other, a floating cylinder member extending through the bearing collar and provided with oppositely opening cylinder chambers in which the respective pistons are telescopically slideable, said member having a transverse partition between said cylinder chambers and provided with a port, a valve controlling said port said valve being provided with a projecting stem andA the piston having its passage connected with the pressure input conduit being provided with means against which said stem abuts when said partition approaches said piston to unseat said valve, pneumatic pistons in the respective pneumatic cylinders, each of said pneumatic pistons having an annular diaphragm seal peripherally engaged between the flanges of the pans of its respective pneumatic cylinder, the said pneumatic pistons being mounted at spaced points on said member, and said member having longitudinal passages, one of which extends through one of said pneumatic pistons, and the other of which extends through the other of said pneumatic pistons, each of said passages extending through said bearing collar and opening into the next pneumatic cylinder between said collar and the pneumatic piston in the pneumatic cylinder in which said passage opens.

8. In a device of the character described, the combination of a series of pneumatic cylinder shells, bearing-collar means connecting contiguous portions of the shells in said series, a hydraulic displacement member reciprocable through said bearing collar means, pneumatic pistons in the respective shells mounted on said member and provided with sealing connection with their respective shells, said pneumatic pistons defining corresponding chambers and opposing corresponding chambers in said shells, and means for developing and regulating pneumatic pressure differential between said corresponding chambers and said opposing corresponding chambers whereby to effect pneumatic piston movement in said shells, the said chambers of said shells having conduit connections placing 'said corresponding chambers and said opposing corresponding chambers in communication with each other throughout the series, said conduit connections comprising passages extending longitudinally through said member.

9. The combination set forth in claim 8 in which the pressure regulating means comprises a vacuum connection to corresponding chambers of the several shells, a port communicating with the opposing ,corresponding chambers of the respective shells, a regulating chamber with which said port communicates, said regulating chamber having wall portions provided with high pressure and low pressure ports, valve means mounted for movement respecting said wail portions for the selected opening and closing or" the respective ports last mentioned in alternation, and a hydraulic pressure line and piston operatively connected for effecting relative movement between said valve means and the ports last mentioned.

10. In a hydraulic brake booster in which manually developed hydraulic pressure operates control mechanism to vary the pressure differential in a plurality of pneumatic cylinders in which pneumatic pistons operate to provide power for the operation of a hydraulic brake, the combination of a plurality of pneumatic cylinders comprising shells connected in series, bearing collar means connecting contiguous shells in said se ies, a hydraulic pressure developing member reciprocable through said bearing means Within the series, and a control casing between said shells and comprising a pressure chamber having a nrs-t port `communicating with rst portions of the respective shells, and a second port communicating with second portions of the respective shells, and a :third port communicating with the atmosphere, valve means controlling the second third `ports and disposed Within the casing and hydraulic connections for the operation of said valve means.

11. Ina device of the character described, the combination withpneumatic cylinder shells connected in series, of a band encircling peripheral portions of said shells and defining an air chamber therebetween, and a control casing disposed in said chamber and having a valve controlled port aording communication between said chamber and the interior of said casing.

i2. The combination set forth in claim l1 in which said band has ioraminous wall and is provided with a filter pad disposed to cleanse air admitted through said wall into said chamber.

13. In combination, a pneumatic cylinder, a pneumatic piston reciprocable therein and dividing said-cylindeiinto high pressure and low pressure chambers, a vacuum connection to the low pressure chamber, a hydraulic displacement member with which said piston is connected to actuate said ,pneumatic member in accordance with pressure differentials to which said pneu.- matic piston is subject, a control chamber having a first ,port communicating with the high pressure chamber of said pneumatic cylinder, a second port communicating with the low vpressure chamber ci said pneumatic cylinder, and a third port communicating with the atmosphere, valve seats at the second and third ports, valve means relatively movable respecting the seats for the control of the second and third ports, and an actuator connected with said valve means for effecting relative movement between said valve means and said seats in directions to open the second and third ports alternatively, together with a slave motor comprising `a pneumatic cylinder, a .pneumatic piston dividing said cylinder into high pressure and low pressure chambers, a hydraulic displacement member connected with said pneumatic piston to be actuated thereby, and conduits providing connections between the respective chambers of the slave motor cylinder and the corresponding chambers of the pneumatic cylinder rst mentioned, said hydraulic displacement members kcomprising means inside said f chamber of said cylinder, said control chamber being provided with opposed ports, one of which communicates with the low pressure chamber, and the other with the atmosphere, valve means reciprocable respecting said ports and opening ':i and closing the respective ports in alternation,

said valve means comprising valve seats and an operating rod provided with disks floating on said rod and engageable with said seats in the course ci recprocation of the rod, said seats being suiiiciently to allow said disks to seat simultaneously at the opposed ports, and a compression spring interposed between said disks and urging them toward the respective seats.

l5. In a device of the character described, a booster cylinder having a piston sub-dividing such cylinder into high pressure and lo-w pressure chambers, in combination with a vacuum connection to one ci said chambers, and a control mechanism including a control chamber communicating with the high pressure chamber of said cylinder, said control chamber having a port and valve seat, a valve for said seat, said valve being adapted when open to admit atmosphere through said seat to said control chamber, a seco-nd chamber in communication with the low pressure chamber of said cylinder and provided with a seat portion engageable with said valve, and means for effecting relative movement of said second control chamber respecting said rst seat for moving the second seat to and from the valve and for displacing the valve from the rst seat.

16. Control mechanism of the character described comprising a casing having iirst and second ports and provided with a seat about the second port, a valve engaging said seat and movable outwardly therefrom, a spring biasing said valve toward its said seat, a shell within said casing and provided with a tubular portion disposed within said second port and provided with a second seat for said valve, means guiding said shell for axial reciprocation through said second port, Vpacking between said shell and said casing whereby to provide a sealed chamber within said casing, and means for reciprocating said shell within said casing through a range which includes one rposition in which the second seat is spaced from said valve, a second position in which said second seat is engaged with said valve while said valve is engaged with said 'lrst seat, and a third position in which said shell has displaced said valve from engagement with said rst seat, said chamber'being thereby in selective communication either with the atmosphere through said valve, or with the interior of said shell.

17. In a booster mechanism for hydraulic brakes, the combination with a pneumatic cylinder and a piston provided with packing in said cylinder and sub-dividing said cylinder into high pressure and low pressure chambers, a hydraulic brake operating pump including relatively movable piston and cylinder members, one of which is connected with said pneumatic ypiston to receive motion therefrom for hydraulic displacement to operate .a brake, said pneumatic cylinder having a vacuum connection to its low pressure chamber, a regulating device comprising valve means for selectively placing the high pressure chamber in communication selectively with the low pressure chamber and alternatively with the atmosphere, a hydraulic motor including a cylinder and piston, the piston being connected with said valve means for the operation thereof, a diaphragm chamber provided with a diaphragm connected with said motor piston and valve means, said diaphragm chamber being operatively connected with the high pressure chamber aforesaid to be subject to atmospheric pressure when the high pressure chamber is open to the atmosphere, said diaphragm having its other face in communication with the low pressure chamber and subject to vacuum, and a hydraulic connection to said motor cylinder including a brake pedal and master cylinder, whereby said brake pedal actuates said valve means subject to increasing opposition of said diaphragm according to the differential pressure between the high and low pressure chambers of said pneumatic cylinder, in further combination with a hydraulic line from said master cylinder to said pump and including a check valve adapted for automatic closing to prevent the return to said master cylinder of pressure developed in said pump in excess of that developed in the master cylinder.

18. In a booster mechanism for hydraulic brakes, the combination with a pneumatic cylinder and a piston provided with packing in said cylinder and sub-dividing said cylinder into high pressure and low pressure chambers, a hydraulic brake operating pump including relatively movable piston and cylinder members, one of which is connected with said pneumatic piston to receive motion therefrom for hydraulic displacement to operate a brake, said pneumatic cylinder having a vacuum connection to its low pressure chamber, a regulating device comprising valve means for selectively placing the high pressure chamber in communication selectively with the low pressure chamber and alternatively 'with the atmosphere, a hydraulic motor including a cylinder and piston, the piston being connected with said valve means for the operation thereof, a diaphragm chamber provided with a diaphragm connected with said motor rpiston and valve means, said diaphragm chamber being operatively connected with the high pressure chamber aforesaid to be subject to atmospheric pressure when the high pressure chamber is open to the atmosphere, said diaphragm having its other face in communication with the low pressure chamber and subject to vacuum, and a hydraulic connection to said motor cylinder including a brake pedal and master cylinder, whereby said brake pedal actuates said valve means subject to increasing opposition of said diaphragm according to the differential pressure between the high and low pressure chambers of said pneumatic cylinder, in further combination with a hydraulic line from said master cylinder to said pump and including a check valve adapted for automatic closing to prevent the return to said master cylinder of pressure developed in said pump in excess of those developed in the master cylinder, and a stop disposed in the path of movement of the pump member connected with the pneumatic piston, said check valve being mounted in said member and including a stem engageable with said stop for displacement to open the valve in one ex-' treme position of said last mentioned member.

19. In a, device of the character described, the combination with at least one pneumatic cylinder having a pneumatic piston operable therein and provided with packing whereby to divide said pneumatic cylinder into two chambers, one of said chambers having a vacuum connection, a control mechanism comprising valve seats, ports and passages, and valve actuating means for selectively placing the second chamber of said cylinder alternatively in communication with the first chamber and with the atmosphere, and a slave motor comprising a pneumatic cylinder and a packed pneumatic piston reciprocable therein and dividing the slave motor cylinder into two chambers, and conduits connecting the chambers of the slave motor cylinder with respect to chambers of the pneumatic cylinder first mentioned, a hydraulic cylinder and piston connected for actuation by the pneumatic cylinder piston iirst mentioned, a master hydraulic cylinder connected to said hydraulic cylinder, said master cylinder also having a connection to said control mechanism for the actuation of said control mechanism, said slave motor being provided with a hydraulic cylinder and piston connected for actuation by said slave motor pneumatic piston, and a supply of hydraulic fluid separate from said master cylinder for said slave motor hydraulic cylinder.

20. The device of claim 19 in which said control mechanism comprises a control chamber communicating with said second chamber of the "l cylinder rst mentioned, the control chamber being defined by walls having two separate ports with respect to which said valve means has relative movement, together with means for effecting such movement which includes a hydraulic motor including a hydraulic cylinder and piston members, a support to which one of said members is fixed, and a connection from the other of said members for eiecting such movement.

2l. The combination set forth in claim 19 in which at least one of the pneumatic cylinders has a companion pneumatic cylinder with a piston provided with a pneumatic connection to the piston of said one cylinder, and chambers having passage extensions to the respective chambers of the cylinder first mentioned.

22. In a device of the character described, a series of pneumatically connected cylinders, each comprising a pair of oppositely dished fianged pans, pneumatic pistons reciprocable in the several cylinders, diaphragms connected peripherally with the respective pneumatic pistons and clamped between the iianges of the respective pans to constitute packing for said pneumatic pistons, a hydraulic pump comprising hydraulic piston and cylinder members, one of Which is connected to the several pneumatic pistons to receive motion therefrom, each of the pneumatic pistons dividing its pneumatic cylinder into high and low pressure chambers, and the said one pump member including passages connecting the several corresponding chambers of the several pneumatic cylinders of said series, a brake operating conduit leading from the other of said pump members, said other pump member being fixed to a pneumatic cylinder at the end of said series, a hydraulic operating circuit including a master cylinder and pedal operated piston therein, and a duct leading therefrom to said pump, a check valve controlling reverse flow from said pump to said duct, a vacuum connection to the arf-cams low pressure chambers .of the .several pneumatic cylinders, control mechanism including 'ports and 'valve '.mean's Vfor selectively vcoupling the high pressure chambers of the several pneumatic cylinders alternatively .to 'the low pressure chambers and to :the atmosphere, a hydraulic motor operatively connected 'with said valve means .for the actuation thereof, and a by-.pass from said master cylinder 'duct to said motor.

23. The "combination set forth .iin claim 22 iin further combination Vwith a diaphragm chamber including a diaphragm `connected to lsaid :motor and having one of its .faces exposed to pressures in Yone of said chambers, :and the other of :its faces exper-ed to pressures in the other `of ysaid chambers, the diirerential 'of saidpressuressbeing exerted in vopposition .to the operation 'of said valve means by saidpump.

24. A pneumatic booster for hydraulic brake operating ymechanism comprising :series .of pneumatic cylinders, each including apair of oppositely `dished anged pans, .fa bearing `collar connected between contiguous Ypans of consecutive cylinders, a hydraulic cylinder reciprocable through said bearing collar within the pneumatic cylinders and Yprovided with oppositel-y opening cylinder cavities, pneumatic pistons in the respective ,pneumatic cylinders, Vpacking diaphragms connectedperipherally with said pneumatic lpistons and clamped between the I'ianges of .the pneumatic cylinders, hydraulic `pistcns fixed within .the pneumatic cylinders at `the cnds of said Yseries and engaged in the respectiveacavities of the hydraulic cylinder, passages extending longitudinally of the hydraulic ycylinder and communicating between corresponding portions of the respective `pneumatic .cylinders whereby the respective pneumatic pistons will be subject to corresponding :pressure diiierentials, hydraulic ducts extending through .the respective :fixed hydraulic ,pistons aforesaid and .communicatir-1gI with .the respective cavities, a partition between said cavities `provided with a port, a check valve in said port, a vacuum connection communicating with one oi said pneumatic cylinders and through one of said passages longitudinally of said rhydraulic cylinder with another pneumatic cylinder, and a control mechanism comprising valve means for selectively coupling other portions oi the pneumatic cylinders with a source of vacuum and alternatively with atmospheric air, and `a hydraulic connection with said valve means vfor the actuation thereof and having .a branch connection with the hydraulic piston duct from which such check valve opens.

.25. The device of claim 24 in Whichsaid control mechanism comprises a control chamber having a first port opening into one of said pneumatic cylinders and having Wall portions provided respectively with second `and third ports and seats, said motor vbeing connected to eiect 1'6 relative .movement :between ,said lseats vand valve means.

.-26. The combination lset ,forth .fin claim 24 :in Which said control mechanism is disposed between two of saidpneumatic cylinders 4'and encircled nby a loan-cl, connecting said cylinders peripherally.

27. The combination Aset forth vin claim 24 which said :control vmechanism is located vremote from the pneumatic cylinders andprovided rwith conduits leading thereto and ycomrrrunicatirrg therewith at opposite 'sides :of the respective ,pistons therein, said control mechanism including a control chamber having a rst port 'opening :to one 'of vsaid conduits-a, vsecond rportfopening to the other, Iand a third port opening .to the atmosphere, said .valve means providing relative-'opening .and closing of .said second and third ports.

28. .The combination set forth lin claim 24 .in which .said controllmechanism is located remote from the pneumatic cylinders and p1'ovidedwith conduits .leading thereto and vcommunicating therewith lat vopposite `sides of the `respective :pis-

tons therein, said 'control mechanism .including @a control chamber having a rlrst -`port opening to oneof said conduits,fa second portopening ftoth'e other, and a third port opening to 'the :atmosphere, vsaid valve 'means 'providing relative fopening and closing of :said .second and third iper-ts, said control mechanism .further vincluding :a hydraulic motor comprising said hydraulic r,connection and a diaphragm connected withfsai'd valve means in opposition to the motor :operated ldisplacement thereof and communicating on :ione facewith the rst port fand ron the other :fac'ewith the second-port, 'whereby to be -subjiect tto `a "idiierential correspondin'gtoithat exstingin fthe pneumatic cylinders.

References yCited yfn "the sle 0f iths ,patent UNITED STATES PATENTS Number Name vDatc v1,l72,801 vLoue-head INov. f6, T1923 l'2,289,043 Rockwell J11y'7 1942 2,305,638 Rockwell Dec. 22, 19.42 2,322,739 Vanderzee .June 122, 1943 2,352,357 Almond .June 27, 1944 2,353,755 :Price ,July l18, 1944 l2,383,082 Rossmann Aug. 21, 21945 v2,393,524 .Fant Jan. 22, 11946 2,406,328 Gunderson Aug. .27, y192156 2,434,588 Rockwell Jan. .13, 19.48 2,470,748 Thomas'et al. May '17,1949 2,587,803 .Adams Mar. 4, r11-952 r'F(TtliIChT PATENTS Number 'Country Date 329,680 France 'June16, lT903 

